Separation membrane composite and method for manufacturing separation membrane composite

Abstract

A separation membrane composite (1) includes: a porous support (11); and a separation membrane (12) provided on the support (11) and composed of a metal-organic structure. The separation membrane (12) includes: a particle-containing layer (16) which is a layer in contact with the support (11) and in which particulate particles (161) of the metal-organic structure are dispersed; and a dense layer (17) which is a layer in contact with the particle-containing layer (16) on the side opposite to the support (11) and does not contain the particulate particles (161). In a cross section perpendicular to the surface of the separation membrane (12), the area ratio of the particulate particles (161) in the particle-containing layer (16) is 5 to 90%. Thus, generation of cracks in the separation membrane (12) can be suppressed.

Description

Technical Field

[0001] This invention relates to a separation membrane composite and a method for manufacturing the separation membrane composite.

[0002] [Reference to relevant applications]

[0003] This application claims priority to Japanese Patent Application JP2024-030483, filed on February 29, 2024, the entire disclosure of which is incorporated herein by reference. Background Technology

[0004] In recent years, with the global commitment to carbon neutrality, the demand for technologies that separate and recover carbon dioxide (CO2) contained in industrial waste gases emitted from factories and other sources (CO2 / N2 separation) has been increasing. On the other hand, metal-organic frameworks (MOFs) are porous materials with high surface areas. By forming membranes on porous supports in the same manner as zeolite membranes, they are expected to be used in various applications such as gas and liquid separation. For example, the paper "Highly CO2 Selective Metal-Organic Framework Membranes with Favorable Coulombic Effect" (Advanced Functional Materials, 2021, Vol. 31, 2006924) (Reference 1) by Da-Shiuan Chiou et al. discloses an MOF called "CAU-10-H" in which seed crystals are attached to a support (substrate) and crystal particles are grown from the seed crystals, thereby forming a CAU-10-H MOF membrane on the support. It should be noted that Japanese Patent Application Publication No. 10-57784 (Document 2) states that in zeolite membranes with internal bridging structures (voids), the strength of the bridging structure portion is relatively weak, and therefore, the pressure resistance deteriorates.

[0005] However, in separation membrane composites where a separation membrane is formed on a support, heat treatment is performed to remove solvents that have entered the pores of the separation membrane during cleaning. At this time, stress caused by the difference in thermal expansion rates between the support and the separation membrane can easily lead to cracks in the separation membrane. When the separation membrane is composed of MOF (Metal-Oxide-Flattened Foil), the grain boundary strength of MOF is relatively low, making it particularly prone to cracking. Reference 1 suggests that drying the MOF membrane at 70°C for one day after formation and cleaning increases the likelihood of crack formation. Furthermore, even at heating temperatures below 70°C, durability during long-term use can sometimes be problematic depending on the operating environment. Summary of the Invention

[0006] The purpose of this invention is to suppress the formation of cracks in separation membranes composed of MOF.

[0007] The invention of Scheme 1 is a separation membrane composite comprising: a porous support; and a separation membrane disposed on the support, which is composed of a metal-organic structure, the separation membrane comprising: a particle-containing layer in contact with the support, wherein particulate particles of the metal-organic structure are dispersed in the particle-containing layer; and a dense layer in contact with the particle-containing layer on the opposite side of the support, which does not contain the particulate particles, wherein in a cross-section perpendicular to the surface of the separation membrane, the particulate particles occupy an area fraction of 5 to 90% in the particle-containing layer.

[0008] According to the present invention, it is possible to suppress the formation of cracks in separation membranes composed of metal-organic structures.

[0009] The invention of Scheme 2 is based on the separation membrane complex of Scheme 1, wherein the particulate particles include aggregates of microparticles.

[0010] The invention of Scheme 3 is based on the separation membrane composite of Scheme 1 or 2, wherein the average particle size of the granular particles is 10 to 500 nm.

[0011] The invention of Scheme 4 is based on the separation membrane composite of any one of Schemes 1 to 3, wherein the thickness of the particle-containing layer is less than 1 μm.

[0012] The invention of Scheme 5 is based on the separation membrane composite of any one of Schemes 1 to 4, wherein the average membrane thickness of the separation membrane is 1.1 to 20 times the thickness of the particle-containing layer.

[0013] The present invention also relates to a method for manufacturing a separation membrane composite.

[0014] The invention of Scheme 6 is a method for manufacturing a separation membrane composite, comprising the following steps: a) preparing metal-organic structure particles; b) preparing a dispersion containing an organic solvent and water as solvents, and containing the particles and a pH adjuster, wherein the aggregates of the particles are dispersed as seed crystals; c) using the dispersion to attach the seed crystals to a porous support; and d) immersing the support in a raw material solution and using solvothermal synthesis to form a separation membrane composed of a metal-organic structure on the support.

[0015] The invention of Scheme 7 is based on the manufacturing method of the separation membrane composite of Scheme 6, wherein the ratio of the organic solvent in the solvent of the dispersion is 90% by volume or more, and the ratio of water is 10% by volume or less.

[0016] The invention of Scheme 8 is based on the manufacturing method of the separation membrane composite of Scheme 6 or 7, wherein the average particle size of the aggregates in the dispersion is 10 to 500 nm.

[0017] The above-mentioned objectives, as well as other objectives, features, solutions, and advantages, will become clear from the following detailed description of the invention with reference to the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of the separation membrane complex.

[0019] Figure 2 This is a magnified cross-sectional view showing a portion of the separation membrane complex.

[0020] Figure 3 This is a cross-sectional view showing the vicinity of the separation membrane.

[0021] Figure 4 This is a diagram illustrating the manufacturing process of the separation membrane composite.

[0022] Figure 5 This is a diagram showing the seed crystals attached to the support.

[0023] Figure 6 This is a diagram used to illustrate the treatment of the comparative example.

[0024] Figure 7 This is a diagram showing the separation device.

[0025] Figure 8 This is a diagram illustrating the separation process of a mixture. Detailed Implementation

[0026] Figure 1 This is a cross-sectional view of the separation membrane complex 1. Figure 2 This is a cross-sectional view showing a portion of the separation membrane composite 1. The separation membrane composite 1 includes a porous support 11 and a separation membrane 12 disposed on the support 11. As described below, the separation membrane 12 is a membrane made of a metal-organic structure (MOF) (hereinafter also referred to as "MOF membrane"), and the separation membrane composite 1 is an MOF membrane composite. An MOF membrane is defined as at least a membrane in which MOF is formed in a membrane form on the surface of the support 11, excluding membranes that merely disperse MOF particles within an organic membrane. Figure 1 In the image, the separation membrane 12 is depicted with bold lines. Figure 2 In the diagram, parallel oblique lines are marked for the separation membrane 12. Additionally, Figure 2 In the process, the thickness of the separation membrane 12 is depicted as thicker than it actually is.

[0027] The support 11 is a porous component that allows gas and liquid to pass through. Figure 1In the example shown, the support 11 is provided along the length direction (i.e.,) of the integrally formed, connected columnar body. Figure 1 The so-called integral support body has multiple through holes 111 extending in the left and right directions. Figure 1 In the example shown, the support 11 is generally cylindrical. The cross-section of each through hole 111 (i.e., compartment) perpendicular to the length direction is, for example, generally circular. Figure 1 In the diagram, the diameter of the through hole 111 is depicted as larger than it actually is, and the number of through holes 111 is depicted as fewer than it actually is. The separation membrane 12 is formed on the inner circumferential surface of the through hole 111, and the inner circumferential surface of the through hole 111 is covered almost entirely.

[0028] The length of the support 11 (i.e., Figure 1 The length (in the left-right direction) is, for example, 10cm to 200cm ("~" means above the preceding value and below the following value). The outer diameter of the support 11 is, for example, 0.5cm to 30cm. The distance between the central axes of adjacent through holes 111 is, for example, 0.3mm to 10mm. The surface roughness (Ra) of the support 11 is, for example, 0.1μm to 5.0μm, preferably 0.2μm to 2.0μm. It should be noted that the shape of the support 11 can be, for example, honeycomb, flat, tubular, cylindrical, prismatic, or polygonal. When the shape of the support 11 is tubular or cylindrical, the thickness of the support 11 is, for example, 0.1mm to 10mm.

[0029] The support 11 is formed, for example, using ceramic. Examples of ceramic sintered bodies selected as materials for the support 11 include: alumina, silica, andalusite, zirconium oxide, titanium dioxide, yttrium oxide, silicon nitride, and silicon carbide. In this embodiment, the support 11 includes at least one of alumina, silica, and andalusite. The support 11 may include an inorganic binder. As an inorganic binder, at least one of titanium dioxide, andalusite, easily sinterable alumina, silica, glass frit, clay minerals, and easily sinterable cordierite may be used.

[0030] The average pore size of the support 11 is, for example, 0.01 μm to 70 μm, preferably 0.05 μm to 25 μm. The average pore size of the support 11 near the surface where the separation membrane 12 is to be formed is 0.01 μm to 1 μm, preferably 0.05 μm to 0.5 μm. For example, the average pore size can be measured using a mercury porosimeter, a pore size distribution measuring device, or a nanoscale pore size distribution measuring device. Regarding the overall pore size distribution of the support 11, including the surface and interior, D5 is, for example, 0.01 μm to 50 μm, D50 is, for example, 0.05 μm to 70 μm, and D95 ​​is, for example, 0.1 μm to 2000 μm. The porosity of the support 11 near the surface where the separation membrane 12 is to be formed is, for example, 20% to 60%. The porosity can be determined as a proportion of the area of ​​the space present in an SEM (scanning electron microscope) image of the cross-section of the support 11.

[0031] The support 11 may be a multilayer structure formed by stacking multiple layers with different average pore sizes in the thickness direction. The average pore size and sintered particle size of the surface layer, including the surface on which the separation membrane 12 is to be formed, are smaller than the average pore size and sintered particle size of the layers other than the surface layer. The average pore size of the surface layer of the support 11 is, for example, 0.01 μm to 1 μm, preferably 0.05 μm to 0.5 μm. When the support 11 has a multilayer structure, the materials of each layer can be the materials described above. The materials of the multiple layers forming the multilayer structure may be the same or different.

[0032] The separation membrane 12 is a porous membrane with micropores. The separation membrane 12 can separate a specific substance from a mixture of multiple substances using molecular sieving or similar methods. In the separation membrane 12, other substances are less likely to permeate than the specific substance. In other words, the permeation rate of the other substances in the separation membrane 12 is lower than that of the specific substance.

[0033] The average thickness of the separation membrane 12 is, for example, 5 μm or less, preferably 2 μm or less. This enables the achievement of high permeation rates. The lower limit of the average thickness of the separation membrane 12 is not particularly limited, but from the viewpoint of improving separation performance, 0.5 μm is preferred, and more preferably 0.7 μm. The method for measuring the average thickness of the separation membrane 12 will be described below. The surface roughness (Ra) of the separation membrane 12 is, for example, 2 μm or less, preferably 1 μm or less, and more preferably 0.5 μm or less.

[0034] The MOF membrane constituting the separation membrane 12 is a polycrystalline membrane mainly composed of a large number of MOF crystals formed on the surface of the support 11. A composite layer 13 is formed near the interface between the separation membrane 12 and the support 11, in which MOF crystals penetrate into the fine pores of the support 11. Figure 2In the diagram, parallel diagonal lines are drawn coinciding with a portion of the support 11, thus illustrating the composite layer 13. The composite layer 13 is a part of the support 11. The thickness of the composite layer 13 is, for example, 2 μm or less. Accordingly, the decrease in transmission velocity caused by the presence of the composite layer 13 can be suppressed. Alternatively, the composite layer 13 may be absent, with a lower limit of 0 for its thickness.

[0035] In measuring the thickness of composite layer 13, a section (longitudinal section) perpendicular to the surface of separation membrane 12 is exposed, for example, by section grinding. During SEM observation of this section, the boundary position of composite layer 13 in the direction perpendicular to the surface of support 11 (the interface between support 11 and separation membrane 12) is determined near a measurement location. Specifically, the boundary position on the separation membrane 12 side of composite layer 13 is the position closest to support 11 at the interface between separation membrane 12 and support 11 (the lower end of particle-containing layer 16 described later). The boundary position on the opposite side of composite layer 13 is the edge of the MOF present in the pores of support 11 that is furthest from separation membrane 12 in the depth direction. The distance in the depth direction between the boundary position on the separation membrane 12 side and the boundary position on the opposite side of separation membrane 12 in composite layer 13 is taken as the thickness of composite layer 13 at that measurement location. Furthermore, the average thickness of the composite layer 13 at multiple different measurement locations (e.g., 10 measurement locations) is determined as the thickness of the composite layer 13 in the separation membrane composite 1.

[0036] It is self-evident that the composite layer 13 is absent. In the case of the composite layer 13, there is no separately formed intermediate layer between the support 11 and the separation membrane 12 in the separation membrane composite 1. Therefore, the support 11 and the separation membrane 12 are in direct contact. That is, there is no intermediate layer formed in a process different from the process of forming the MOF membrane between the support 11 and the separation membrane 12.

[0037] The average pore size of the MOF membrane constituting the separation membrane 12 is not particularly limited, but in one example it is greater than 0.40 nm and less than 0.90 nm. "Average pore size of the MOF" refers to the average of the major and minor axes of the pore openings theoretically derived from the framework structure of the MOF. It should be noted that the major and minor axes of the pore openings, more precisely, refer to the inter-lattice spacing of a highly regular lattice structure formed by metal ions and organic ligands. Depending on the structural type, MOFs have a unique pore structure consisting of channels (pores) and cages (internal spaces). Here, the pore size refers to the pore size of the channels. The largest diameter in the cross-section of the channel is defined as the major axis, and the diameter of the cross-section in a direction approximately perpendicular to the major axis is defined as the minor axis. The arithmetic mean of the minor and major axes is then defined as the average pore size. This average pore size is smaller than the average pore size of the support 11 near the surface where the separation membrane 12 is formed.

[0038] The average particle size of the MOFs constituting the surface of the separation membrane 12 (the surface opposite to the support 11, the surface of the dense layer 17 described later), i.e., the average particle size of the crystal grains, is, for example, 0.1 μm to 2 μm. The average particle size is preferably 1 μm or less, more preferably 0.5 μm or less. In a separation membrane 12 with a smaller average particle size of MOFs at the surface, grain boundary defects caused by excessively large gaps between MOF crystals are reduced, thereby improving separation performance. The average particle size of the MOFs at the surface of the separation membrane 12 is the arithmetic mean of the maximum Freette diameters of multiple MOF particles (e.g., 30 particles) obtained by observation of the membrane surface using SEM. The multiple particles to be measured can be randomly selected from the SEM image.

[0039] The MOF constituting the separation membrane 12 is composed of metal ions and organic ligands (hereinafter referred to as "ligands") coordinated with the metal ions. The metal ions that constitute the MOF are not particularly limited; practically, those selected from Al are preferred. 3＋ Co 3 ＋ Co 2＋ Ni 2＋ Ni ＋ Cu 2＋ Cu ＋ Zn 2＋ Fe 3＋ Fe 2＋ Ti 3＋ and Zr 4＋ At least one of the constituent groups. More preferably, metal ions including those selected from Al. 3＋ Zn 2＋ Ti 3＋ and Zr 4＋At least one type of metal ion from the group consisting of the MOF. Preferably, the MOF contains one type of metal ion, but it may also contain multiple types.

[0040] The ligands that form the basis of a MOF are not particularly limited; however, one example is a bidentate ligand, which is an ion of an organic molecule having two carboxyl groups. This allows for the easy formation of fine pores that allow a particular gas to pass through more easily than other gases. The structure other than the two carboxyl groups is not particularly limited; as a preferred example, the ligand has a heterocyclic ring. Furthermore, regarding the ligand, ligands such as pyridyl or pyrrole groups capable of coordinating with metal ions can be used instead of carboxyl groups.

[0041] Figure 3 This is a diagram showing a cross-section of the separation membrane composite 1 perpendicular to the surface of the separation membrane 12. Figure 3 The image shown is an image of the vicinity of the separation membrane 12 in this cross section (longitudinal section) obtained using ULV-SEM (extremely low accelerating voltage scanning electron microscopy). In the following description, [the text will be incomplete and requires further context]. Figure 3 The image shown is simply referred to as a "cross-sectional image". Furthermore, in the cross-sectional image, the side of the separation membrane 12 in the aforementioned depth direction is referred to as the upper side, and the side of the support 11 is referred to as the lower side. The upper and lower sides in the cross-sectional image are independent of the direction of gravity.

[0042] The separation membrane 12 comprises a particle-containing layer 16 and a dense layer 17. The particle-containing layer 16 contacts and covers the surface of the support 11. The dense layer 17 contacts and covers the surface of the particle-containing layer 16 on the opposite side from the support 11. The dense layer 17 does not contact the surface of the support 11. In this way, the particle-containing layer 16 is located above the support 11 and below the dense layer 17, directly sandwiched between the two. The particle-containing layer 16 and the dense layer 17 respectively comprise MOF crystals and grain boundaries. A grain boundary is a region between adjacent MOF crystals. Grain boundaries include, for example, amorphous (i.e., non-morphic), crystalline structures other than MOF crystals, and / or voids.

[0043] The particle-containing layer 16 also includes MOF granular particles 161. The granular particles 161 are present within the particle-containing layer 16 along the interface with the support 11. The granular particles 161 are dispersed within the particle-containing layer 16. The shape of the granular particles 161 in the cross-sectional image is, for example, slightly rounded. The particle-containing layer 16 is a layer containing granular particles 161, and the dense layer 17 is a layer without granular particles 161. The MOF crystal content in the dense layer 17 without granular particles 161 is higher than the MOF crystal content in the particle-containing layer 16. That is, the dense layer 17 is a layer in which the MOF crystals are more densely arranged than in the particle-containing layer 16. Typically, the types of MOF contained in the dense layer 17 are the same as those contained in the particle-containing layer 16. Accordingly, the separation membrane 12 can be easily formed.

[0044] In the synthesis of the separation membrane 12 described later, aggregates of MOF microparticles (secondary particles) are used as seed crystals. Particulate particles 161 are considered to be seed crystals remaining after the synthesis of the separation membrane 12, and the particle-containing layer 16 can be considered a seed-containing layer. Typically, particulate particles 161 comprise aggregates of microparticles, and particles caused by microparticles are identified in the particulate particles 161 in the cross-sectional image. The average particle size of the MOF microparticles, which are primary particles, is, for example, 2–100 nm, preferably 3–50 nm. In cases where the particle size of the MOF microparticles is relatively large, or multiple microparticles constitute an aggregate, particles may not be identified in the particulate particles 161 in the cross-sectional image.

[0045] The average particle size of the granular particles 161 (i.e., the average particle size of the granular particles 161 as secondary particles) is, for example, 10–500 nm, preferably 50–300 nm. In determining the average particle size of the granular particles 161, firstly, the particle size of the granular particles 161 is calculated based on the arithmetic mean of the major and minor axes (the maximum diameter and the diameter in a direction approximately perpendicular to the maximum diameter) of the granular particles 161 in the cross-sectional image. Then, the arithmetic mean of the particle sizes of a predetermined number (e.g., 30) of the granular particles 161 is calculated as the average particle size of the granular particles 161. The granular particles 161 to be measured can be randomly selected from the cross-sectional image. Depending on the thickness of the separation membrane 12, the average particle size of the granular particles 161 (and the seed crystals described later) can be outside the range of 10–500 nm.

[0046] Figure 3 In the cross-sectional image, the uppermost granular particle 161a, located at its uppermost point, has a line perpendicular to the depth direction at its uppermost point, which marks the upper end of the particle-containing layer 16. Similarly, the lowermost particle 110a, located at its uppermost point among the particles 110 forming the surface of the support 11 (i.e., the particles 110 at each position along the surface direction of the support 11), has a line perpendicular to the depth direction at its uppermost point, which marks the lower end of the particle-containing layer 16. Figure 3 In the diagram, the region containing particle layer 16 is enclosed by a rectangle with thick lines, and the thickness of particle layer 16 is indicated by arrow T1.

[0047] In the cross-sectional image, the area fraction of particulate particles 161 in the particle-containing layer 16 (i.e., the ratio of the sum of the areas of particulate particles 161 to the area of ​​the particle-containing layer 16, hereinafter also referred to as the "area fraction of particulate particles 161") is 5% to 90%. Accordingly, as described later, the occurrence of cracks in the separation membrane 12 is suppressed. The lower limit of the area fraction of particulate particles 161 in the particle-containing layer 16 is preferably 10%, more preferably 20%, and even more preferably 30%. The upper limit of the area fraction of particulate particles 161 can be 85% or 80%. In the determination of the area fraction of particulate particles 161, for the separation membrane composite 1, cross-sectional images of 5 fields of view (30,000x) are obtained using ULV-SEM, and the arithmetic mean of the area fraction of particulate particles 161 in the 5 fields of view is determined as the area fraction of particulate particles 161 in the separation membrane composite 1.

[0048] The thickness T1 of the particle-containing layer 16 is the distance in the depth direction between the upper and lower ends of the particle-containing layer 16. The thickness T1 of the particle-containing layer 16 is, for example, 1 μm or less, preferably 0.8 μm or less. If the particle-containing layer 16 is too thick, defects may occur under higher pressure. To more reliably suppress crack formation in the separation membrane 12, the thickness of the particle-containing layer 16 is, for example, 0.1 μm or more, preferably 0.2 μm or more. Similar to the area ratio of the granular particles 161, the arithmetic mean of the thickness of the particle-containing layer 16 in five cross-sectional images of different fields of view is taken as the thickness T1 of the particle-containing layer 16 in the separation membrane composite 1.

[0049] Preferably, the average thickness of the separation membrane 12 is 1.1 to 20 times the thickness of the particle-containing layer 16. This prevents the particle-containing layer 16 from being too thin or too thick in the separation membrane 12. The thickness of the separation membrane 12 is the distance in the depth direction between the lower end of the particle-containing layer 16 and the upper end of the dense layer 17. The upper end of the dense layer 17 is the uppermost position on the surface of the dense layer 17 (the surface opposite to the support 11) in the cross-sectional image. Similar to the area ratio of the granular particles 161, the arithmetic mean of the thicknesses of the separation membrane 12 in five cross-sectional images is determined as the average thickness of the separation membrane 12 in the separation membrane composite 1. Depending on the design of the separation membrane composite 1, the thickness of the particle-containing layer 16 can be greater than 1 μm, and the average thickness of the separation membrane 12 can be greater than 20 times the thickness of the particle-containing layer 16.

[0050] Next, refer to Figure 4The manufacture of the separation membrane composite 1 will be described. In manufacturing the separation membrane composite 1, firstly, MOF microparticles are prepared for later use (step S11). In the preparation of the MOF microparticles, MOF powder is generated by solvothermal synthesis (when the solvent is water, it is also called hydrothermal synthesis) using, for example, water and / or an organic solvent. The MOF powder can be generated using any or known manufacturing method. Next, the MOF powder is pulverized using a ball mill or the like to obtain MOF microparticles. The average particle size (D50) of the MOF microparticles is, for example, 200 nm or less, preferably 2 to 100 nm. When MOF powder with a smaller particle size is generated by solvothermal synthesis, the pulverization of the MOF powder can be omitted, and it can be directly treated as MOF microparticles. The average particle size of the MOF microparticles can be determined using laser scattering (the same applies to the particle size of the seed crystals described later).

[0051] Next, a dispersion containing an organic solvent and water as solvents, and containing MOF particles and a pH adjuster, is prepared (step S12). For example, if the MOF powder is pulverized in an organic solvent, the dispersion can be prepared by adding an aqueous solution of a pH adjuster to the organic solvent containing the pulverized MOF particles. Typically, the pH adjuster is an alkaline or acidic substance, such as sodium hydroxide (NaOH), hydrogen chloride (HCl), nitric acid (HNO3), etc. The aqueous solution of the pH adjuster is an alkaline or acidic aqueous solution. The dispersion is then stirred, causing the MOF particles (primary particles) to agglomerate, resulting in a dispersion in which MOF particle aggregates (secondary particles) are dispersed as seed crystals. The average particle size (D50) of these aggregates in the dispersion is, for example, 10–500 nm, preferably 50–300 nm.

[0052] The goal is to form aggregates with a desired average particle size. The pH of the dispersion, the ratio of organic solvent to water in the solvent of the dispersion, etc., can be arbitrarily determined. In this processing example, the ratio of organic solvent is 90% by volume or more and less than 100% by volume. The ratio of organic solvent can be 80% by volume or more. The component in the solvent of the dispersion other than the organic solvent is water, and the ratio of water in this solvent is greater than 0% by volume and less than 10% by volume. By including water in the dispersion, it is easier to form aggregates by adjusting the pH. In addition, by keeping the water ratio at less than 10% by volume, the dissolution of particles can be suppressed. The concentration of MOF particles (solids) in the dispersion is, for example, 0.01 to 1% by weight.

[0053] Next, the dispersion obtained by dispersing the seed crystals in a solvent is brought into contact with a portion of the separation membrane 12 to be formed on the support 11, thereby attaching (carrying) the seed crystals to the support 11 (step S13). For example, a dip-coating method can be used, in which the seed crystals are attached to the support 11 by immersing the porous support 11 in the dispersion. Figure 5As shown, seed crystal 81 is attached to support 11 in the form of an aggregate of MOF particles (secondary particles). The solvent is then removed by drying, thereby creating a support with the seed crystal attached. Seed crystals can also be attached to support 11 using other methods.

[0054] Next, a raw material solution (also called a synthetic sol or synthetic solution) for the formation of separation membrane 12 is prepared for later use. The raw material solution can be prepared in advance. In preparing the raw material solution, a solvent (water and / or an organic solvent), a ligand, a metal ion source, etc., are mixed. For example, a ligand is added to the solvent, and the ligand is dissolved using ultrasonic treatment or heating in a constant temperature bath. Then, metal ions are added to obtain the raw material solution.

[0055] After the raw material solution is prepared, the support 11 with seed crystals attached is immersed in the raw material solution. Then, the raw material solution is heated, thereby initiating solvothermal synthesis, including hydrothermal synthesis (hereinafter collectively referred to as "solvothermal synthesis"). In solvothermal synthesis, the MOF grows starting from the seed crystals, and a MOF film, namely the separation film 12, is formed on the support 11 (step S14). Figure 5 In the diagram, the separation membrane 12 is represented by a double-dotted line. Within the separation membrane 12, a large number of seed crystals 81 are entirely or partially contained in granular form 161 (see reference). Figure 3 The residue remains in the form of ). The synthesis temperature (heating temperature of the raw material solution) during solvothermal synthesis is, for example, 40–200°C, preferably 70–150°C. The solvothermal synthesis time is, for example, 1–100 hours, preferably 1–50 hours.

[0056] The preferred feedstock solution for solvothermal synthesis is one that, if solvothermal synthesis is performed without the seed crystals 81 adhering to the support 11, does not readily form a MOF film on the support 11, i.e., does not readily generate MOF nuclei. Such a feedstock solution is prepared by diluting the original feedstock solution or by changing the composition of the metal ion source and ligands. By using this feedstock solution, the interparticle spaces in the seed crystals 81 can be maintained, and the MOF can grow from the seed crystals 81, more reliably forming a separation film 12 in the form of granular particles 161 remaining from the seed crystals 81.

[0057] After the solvothermal synthesis is completed, the support 11 and the separation membrane 12 are washed with pure water, and then with ethanol or the like. It is preferable to repeat the washing with water and ethanol multiple times. The washed support 11 and the separation membrane 12 are then dried, for example, at 100°C. "Drying" means removing the molecules of the washing substances such as water and ethanol from the pores of the separation membrane 12. Through the above treatment, the separation membrane composite 1 is completed.

[0058] Here, the treatment of comparative examples related to the formation of the separation membrane is described. Figure 6This diagram illustrates the treatment of the comparative examples. In the comparative examples, the seed crystals dispersed in the dispersion were in the form of primary particles, and the primary seed crystals 91 adhered to the support 11. In this case, although the reason is unclear, very few seed crystals remained in the form of granular particles in the separation membrane 92 formed by solvothermal synthesis. That is, there was essentially no particle-containing layer in the separation membrane 92, or even if there was, the area ratio of granular particles in the particle-containing layer was less than 5%. Furthermore, in the separation membrane composite having such a separation membrane 92, as in Comparative Examples 1 to 3 described later, the separation performance decreased significantly after heating the separation membrane composite. The reason for the decrease in separation performance is believed to be that when the separation membrane composite is heated, stress caused by the difference in thermal expansion coefficients between the support 11 and the separation membrane 92 causes cracks to form in the separation membrane 92.

[0059] In contrast, Figure 3 In the separation membrane composite 1, the separation membrane 12 comprises: a particle-containing layer 16, which is in contact with the support 11, wherein particulate particles 161 of MOF are dispersed therein; and a dense layer 17, which is in contact with the particle-containing layer 16 on the side opposite to the support 11, and does not contain particulate particles 161. In a cross-section of the separation membrane composite 1 perpendicular to the surface of the separation membrane 12, the particulate particles 161 occupy an area fraction of 5 to 90% in the particle-containing layer 16. In such a separation membrane composite 1, as in Examples 1 to 10 described later, there is almost no decrease in the separation performance of the separation membrane composite 1 after heating. Therefore, it is believed that the stress generated in the separation membrane 12 during heating is mitigated by the presence of a certain amount of particulate particles 161, and the generation of cracks in the separation membrane 12 can be suppressed.

[0060] Preferably, the granular particles 161 comprise an aggregate of MOF microparticles. In this case, the presence of voids between the MOF microparticles (primary particles) within the granular particles 161 more reliably mitigates the stress generated during heating of the separation membrane composite 1, thereby further suppressing crack formation in the separation membrane 12. As mentioned above, it is not necessarily necessary to confirm the aggregation (particles) of the microparticles 161 in the cross-sectional image.

[0061] The method for manufacturing the separation membrane composite 1 includes the following steps: preparing MOF microparticles; preparing a dispersion containing an organic solvent and water as solvents, and containing microparticles, a pH adjuster, and microparticle aggregates as seed crystals; using the dispersion, attaching the seed crystals to a porous support 11; and immersing the support 11 in a raw material solution, and using solvothermal synthesis to form a separation membrane 12 composed of MOF on the support 11. Accordingly, a separation membrane composite 1 capable of suppressing crack formation in the separation membrane 12 can be easily manufactured.

[0062] Next, examples and comparative examples of the separation membrane complex will be described. Table 1 shows the types of MOFs and various measurement results for the examples and comparative examples.

[0063] Table 1

[0064]

[0065] First, the fabrication of three types of MOF seed crystals, namely “Al Fumarate”, “KMF-1”, and “UiO-66-NH2”, will be described. In each embodiment and comparative example, any one of the three seed crystals was used.

[0066] <Preparation of Al Fumarate Seeds>

[0067] First, a mixed solution was prepared by adding 0.28 g of fumaric acid and 0.34 g of sodium formate as ligands to 30 mL of deionized water. Next, 0.83 g of aluminum sulfate 18 hydrate as a metal ion source was added to the mixed solution. Then, the solution was subjected to solvothermal synthesis in an autoclave at 120 °C for 12 hours. The precipitate was separated using a centrifuge and washed three times with deionized water and ethanol. Finally, it was dried at 100 °C for 24 hours to obtain Al Fumarate powder.

[0068] 1 g of the above powder, 30 g of ZrO2 spheroids with a diameter of 1 mm, and 9 mL of ethanol were placed into a 25 mL glass vial. The vial was then mounted on a ball mill stand, and the powder was pulverized at 200 rpm for 20 hours. The particle size (D50) of the obtained particles was 40 nm, as determined by laser diffraction / scattering particle size distribution measurement. 1 mL of 0.01 mol / L NaOH aqueous solution was added to the ethanol containing these particles, and the mixture was stirred for 10 minutes to allow the particles to aggregate. This yielded an aggregate of Al Fumarate particles, which was used as a seed dispersion. The particle size (D50) of the seed (aggregate) was 250 nm, as determined by laser diffraction / scattering particle size distribution measurement.

[0069] <Preparation of KMF-1 Seed Crystals>

[0070] First, a mixed solution was prepared by adding 1.551 g of 1H-pyrrole-2,5-dicarboxylic acid as a ligand and 1.36 g of sodium formate to 30 mL of deionized water. Next, 3.333 g of aluminum sulfate 18-hydrate as a metal ion source was added to the mixed solution. Then, the solution was subjected to solvothermal synthesis in an autoclave at 120 °C for 12 hours. The precipitate was separated using a centrifuge and washed three times with deionized water and ethanol. Finally, it was dried at 100 °C for 24 hours to obtain KMF-1 powder.

[0071] 1 g of the above powder, 30 g of ZrO2 spheroids with a diameter of 1 mm, and 9 mL of ethanol were placed into a 25 mL glass vial. The vial was then mounted on a ball mill stand, and the powder was pulverized at 200 rpm for 15 hours. The particle size (D50) of the obtained particles was 20 nm, as determined by laser diffraction / scattering particle size distribution measurement. 0.5 mL of 0.01 mol / L NaOH aqueous solution was added to the ethanol containing these particles, and the mixture was stirred for 10 minutes to allow the particles to aggregate. This yielded an aggregate of KMF-1 particles, which was used as a seed dispersion. The particle size (D50) of the seed (aggregate) was 250 nm, as determined by laser diffraction / scattering particle size distribution measurement.

[0072] <Preparation of UiO-66-NH2 seed crystals>

[0073] First, 0.233 g of zirconium chloride as the metal ion source and 0.166 g of 2-aminoterephthalic acid as the ligand were added to a mixed solvent of 3 mL of acetic acid and 30 mL of dimethylformamide (DMF) to prepare a mixed solution. The mixed solution was ultrasonically treated at room temperature for 30 minutes to obtain a homogeneous solution. Next, the solution was subjected to solvothermal synthesis in an autoclave at 120 °C for 24 hours. The precipitate was separated using a centrifuge and washed three times with deionized water and ethanol. Then, it was dried at 100 °C for 24 hours to obtain UiO-66-NH2 powder.

[0074] Without further pulverizing the powder, it was dispersed in 9 mL of DMF. As determined by laser diffraction / scattering particle size distribution measurement, the particle size (D50) of the powder was 90 nm. 0.5 mL of a 0.01 mol / L HCl aqueous solution was added to the DMF containing the powder, and the mixture was stirred for 10 minutes to allow the particles to aggregate. This yielded an aggregate of UiO-66-NH2 particles, which was used as a seed dispersion. As determined by laser diffraction / scattering particle size distribution measurement, the particle size (D50) of the seed (aggregate) was 350 nm.

[0075] <Example 1>

[0076] Ethanol was added to a dispersion of Al Fumarate seeds to prepare a 200 mL dispersion of MOF (Al Fumarate) with a solid content of 0.1 wt% (dispersion for seed support). This dispersion was then brought into contact with a ceramic (alumina) support, and the adhering solvent was dried by air blowing, thereby loading the seeds onto the support.

[0077] Prepare a mixed solution by adding 0.39 g of fumaric acid and 0.45 g of sodium formate to 200 mL of deionized water. Heat the mixed solution to 40 °C and stir for 1 hour. After confirming that the mixed solution becomes clear, cool it to room temperature. Then, add 1.10 g of aluminum sulfate 18 hydrate to the mixed solution to prepare the raw material solution.

[0078] Next, a ceramic support carrying seed crystals and a raw material solution were filled into a Teflon (registered trademark) container and subjected to solvothermal synthesis at 100°C for 20 hours. The resulting membrane composite was washed three times with deionized water and ethanol. Afterward, the membrane composite was left to dry in the atmosphere for at least 12 hours. Through the above treatment, the membrane composite of Example 1, having a membrane composed of Al Fumarate, was obtained.

[0079] <Example 2>

[0080] To prepare a mixed solution, add 0.13 g of fumaric acid and 0.15 g of sodium formate to 200 mL of deionized water. Heat the mixed solution to 40°C and stir for 1 hour. After confirming that the mixed solution becomes clear, cool it to room temperature. Then, add 0.37 g of aluminum sulfate 18 hydrate to the mixed solution to prepare the raw material solution. The process is the same as in Example 1, except as described above.

[0081] <Example 3>

[0082] To prepare a mixed solution, add 0.78 g of fumaric acid and 0.90 g of sodium formate to 200 mL of deionized water. Heat the mixed solution to 40°C and stir for 1 hour. After confirming that the mixed solution becomes clear, cool it to room temperature. Then, add 2.20 g of aluminum sulfate 18 hydrate to the mixed solution to prepare the raw material solution. The process is the same as in Example 1, except as described above.

[0083] <Example 4>

[0084] The solid component used to prepare the MOF was a dispersion for seed support, comprising 0.2% by weight. Everything else was the same as in Example 1.

[0085] <Example 5>

[0086] The temperature and time for solvothermal synthesis were set to 80°C and 10 hours, otherwise the same as in Example 1.

[0087] <Example 6>

[0088] The solid component used to prepare the MOF was a dispersion for seed crystal support, comprising 0.05% by weight. Everything else was the same as in Example 1.

[0089] <Example 7>

[0090] Ethanol was added to the dispersion of KMF-1 seeds to prepare a 200 mL dispersion of MOF (KMF-1) with a solid content of 0.1% by weight (dispersion for seed support). This dispersion was then brought into contact with a ceramic support, and the adhering solvent was dried by air blowing, thereby enabling the seeds to be supported on the support.

[0091] Prepare a mixed solution by mixing 1.551 g of 1H-pyrrole-2,5-dicarboxylic acid and 1.36 g of sodium formate in 200 mL of deionized water. Next, add 3.333 g of aluminum sulfate 18 hydrate to the mixed solution to prepare the raw material solution.

[0092] Next, a ceramic support carrying seed crystals and a raw material solution were filled into a Teflon (registered trademark) container and solvothermal synthesis was performed at 100°C for 20 hours. The resulting membrane composite was washed three times with deionized water and ethanol. Afterward, the membrane composite was left to dry in the atmosphere for at least 12 hours. Through the above treatment, the membrane composite of Example 7, having a membrane composed of KMF-1, was obtained.

[0093] <Example 8>

[0094] The solid component used to prepare the MOF was a dispersion for seed crystal support, comprising 0.2% by weight. Everything else was the same as in Example 7.

[0095] <Example 9>

[0096] DMF was added to a dispersion of UiO-66-NH2 seeds to prepare a 200 mL dispersion of MOF (UiO-66-NH2) with a solid content of 0.1 wt% (dispersion for seed support). This dispersion was then brought into contact with a ceramic support, and the attached solvent was dried by heating and air blowing, thereby loading the seeds onto the support.

[0097] 0.233 g of zirconium chloride and 0.166 g of 2-aminoterephthalic acid were added to a mixed solvent of 3 mL of acetic acid and 30 mL of DMF to prepare a mixed solution. The mixed solution was ultrasonically treated at room temperature for 30 minutes to obtain a homogeneous solution (raw material solution).

[0098] Next, a ceramic support carrying seed crystals and a raw material solution were filled into a Teflon (registered trademark) container and solvothermal synthesis was performed at 120°C for 20 hours. The resulting membrane composite was washed three times with deionized water and ethanol. Afterward, the membrane composite was left to dry in the atmosphere for at least 12 hours. Through the above treatment, the membrane composite of Example 9, having a membrane composed of UiO-66-NH2, was obtained.

[0099] <Example 10>

[0100] The solid component used to prepare the MOF was a dispersion for seed support, comprising 0.2% by weight. Everything else was the same as in Example 9.

[0101] <Comparative Example 1>

[0102] A mixed solution was prepared by adding 0.28 g of fumaric acid and 0.34 g of sodium formate to 30 mL of deionized water. Next, 0.83 g of aluminum sulfate 18 hydrate was added to the mixed solution. The solution was then subjected to solvothermal synthesis in an autoclave at 120 °C for 12 hours. The precipitate was separated using a centrifuge and washed three times with deionized water and ethanol. It was then dried at 100 °C for 24 hours to obtain Al Fumarate powder as seed crystals. As determined by laser diffraction / scattering particle size distribution analysis, the particle size (D50) of the seed crystals was 1200 nm.

[0103] The seed crystals were mixed into ethanol to prepare a 200 mL dispersion of MOF (Al Fumarate) with a solid content of 0.1% by weight (dispersion for seed crystal support). This dispersion was then brought into contact with a ceramic support, and the adhering solvent was dried by air drying, thereby loading the seed crystals onto the support. Unlike Examples 1-10 above, the seed crystals loaded onto the support were not pulverized, and the dispersion did not contain a pH adjuster.

[0104] Prepare a mixed solution by adding 0.39 g of fumaric acid and 0.45 g of sodium formate to 200 mL of deionized water. Heat the mixed solution to 40 °C and stir for 1 hour. After confirming that the mixed solution becomes clear, cool it to room temperature. Then, add 1.10 g of aluminum sulfate 18 hydrate to the mixed solution to prepare the raw material solution.

[0105] Next, a ceramic support carrying seed crystals and a raw material solution were filled into a Teflon (registered trademark) container and solvothermal synthesis was performed at 100°C for 20 hours. The resulting membrane composite was washed three times with deionized water and ethanol. Afterward, the membrane composite was left to dry in the atmosphere for at least 12 hours. Through the above treatment, a membrane composite of Comparative Example 1, having a membrane composed of Al Fumarate, was obtained.

[0106] <Comparative Example 2>

[0107] A mixed solution was prepared by adding 0.28 g of fumaric acid and 0.34 g of sodium formate to 30 mL of deionized water. Next, 0.83 g of aluminum sulfate 18 hydrate was added to the mixed solution. The solution was then subjected to solvothermal synthesis in an autoclave at 120 °C for 12 hours. The precipitate was separated using a centrifuge and washed three times with deionized water and ethanol. Afterward, it was dried at 100 °C for 24 hours to obtain Al Fumarate powder as seed crystals.

[0108] 1 g of the above powder, 30 g of ZrO2 spheroids with a diameter of 1 mm, and 9 mL of ethanol were placed in a 25 mL glass vial, and the powder was pulverized at 200 rpm for 20 hours. As a result of laser diffraction / scattering particle size distribution measurement, the particle size (D50) of the obtained microparticles was 40 nm. Ethanol and water were added to the ethanol containing these microparticles to prepare a 200 mL dispersion (dispersion for seed support) with a MOF solids content of 0.1 wt%, an organic solvent ratio of 80 vol%, and a water ratio of 20%. Unlike Examples 1-10 above, the dispersion did not contain a pH adjuster. Everything else was the same as in Comparative Example 1.

[0109] <Comparative Example 3>

[0110] A mixed solution was prepared by adding 1.551 g of 1H-pyrrole-2,5-dicarboxylic acid and 1.36 g of sodium formate to 30 mL of deionized water. Next, 3.333 g of aluminum sulfate 18-hydrate was added to the mixed solution. The solution was then subjected to solvothermal synthesis in an autoclave at 120 °C for 12 hours. The precipitate was separated using a centrifuge and washed three times with deionized water and ethanol. Afterward, it was dried at 100 °C for 24 hours to obtain KMF-1 powder as seed crystals. As determined by laser diffraction / scattering particle size distribution measurement, the particle size (D50) of the seed crystals was 20000 nm.

[0111] The seed crystals were mixed into ethanol to prepare a 200 mL dispersion of MOF (KMF-1) with a solid content of 0.1% by weight (dispersion for seed crystal support). This dispersion was then brought into contact with a ceramic support, and the adhering solvent was dried by air drying, thereby loading the seed crystals onto the support. Unlike Examples 1-10 above, the seed crystals loaded onto the support were not pulverized, and the dispersion did not contain a pH adjuster.

[0112] Prepare a mixed solution by mixing 1.551 g of 1H-pyrrole-2,5-dicarboxylic acid and 1.36 g of sodium formate in 200 mL of deionized water. Next, add 3.333 g of aluminum sulfate 18 hydrate to the mixed solution to prepare the raw material solution.

[0113] Next, a ceramic support carrying seed crystals and a raw material solution were filled into a Teflon (registered trademark) container and solvothermal synthesis was performed at 100°C for 20 hours. The resulting membrane composite was washed three times with deionized water and ethanol. Afterward, the membrane composite was left to dry in the atmosphere for at least 12 hours. Through the above treatment, a membrane composite of Comparative Example 3, having a membrane composed of KMF-1, was obtained.

[0114] <Various Determinations of Separation Membranes>

[0115] In each of the separation membrane complexes in Examples 1-10 and Comparative Examples 1-3, cross-sectional images showing the longitudinal section of the separation membrane were captured using a ULV-SEM (Extremely Low Accelerating Voltage Scanning Electron Microscope). A ZEISS GeminiSEM460 was used as the ULV-SEM, set to an accelerating voltage of 1 kV and a magnification of 30,000x, to obtain secondary electron images of the inner lens. (Refer to...) Figure 3 As explained, the uppermost point of the granular particle in the cross-sectional image, perpendicular to the depth direction, is designated as the upper end of the particle-containing layer. The lower end of the particle (alumina particle) forming the surface of the support, perpendicular to the depth direction, is designated as the uppermost point of the particle-containing layer.

[0116] For each separation membrane complex, cross-sectional images of five fields of view were obtained. The area ratio of particulate matter in the particle-containing layer in each cross-sectional image was calculated, and the arithmetic mean of the area ratios of particulate matter in the five cross-sectional images was taken as the area ratio of particulate matter in the separation membrane complex. Additionally, the arithmetic mean of the thickness of the particle-containing layer (the distance in the depth direction between the upper and lower ends) in the five cross-sectional images was taken as the thickness of the particle-containing layer in the separation membrane complex. The measurement results of the area ratio of particulate matter and the thickness of the particle-containing layer are shown in the "Area Ratio of Particulate Matter" and "Thickness of Particle-Containing Layer" columns in Table 1. It should be noted that the cross-sectional images confirmed that the particulate matter included aggregates of microparticles, with particle sizes ranging from 10 to 500 nm.

[0117] The thickness of the separation membrane is defined as the distance in the depth direction between the lower end of the particle-containing layer and the upper end of the dense layer. The upper end of the dense layer is defined as the uppermost position of the surface of the dense layer in the cross-sectional image. Similarly, the arithmetic mean of the membrane thicknesses of the separation membrane in the cross-sectional images of the five fields of view is defined as the average membrane thickness of the separation membrane in the separation membrane complex. In Table 1, the average membrane thickness of the separation membrane is shown in the "Membrane Thickness of Separation Membrane" column, and the ratio of the membrane thickness of the separation membrane to the thickness of the particle-containing layer (membrane thickness of separation membrane / thickness of particle-containing layer) is shown in the "Thickness Ratio" column.

[0118] <Determination of the rate of change of CO2 / N2 permeation rate>

[0119] In each separation membrane composite, a mixed gas consisting of 50% CO2 and 50% N2 was introduced onto the surface of the separation membrane at 25°C and 0.3 MPa, and the permeation rates of CO2 and N2 were measured (see below). Figure 7 The separation device 2). Permeability (permeability) refers to the rate at which gas per unit membrane area and unit pressure difference per unit area ...

[0120] Next, the mixed gas was introduced into the surface of the separation membrane at 100°C and 0.3 MPa and maintained at a high temperature for 12 hours. Then, the mixed gas was again introduced into the surface of the separation membrane at 25°C and 0.3 MPa. After confirming that the temperature of the separation membrane composite had decreased, the permeation rates of CO2 and N2 were measured to obtain the CO2 / N2 permeation rate ratio after high-temperature use. The rate of change of the CO2 / N2 permeation rate ratio before and after high-temperature use was calculated by dividing the CO2 / N2 permeation rate ratio after high-temperature use by the CO2 / N2 permeation rate ratio before high-temperature use. The rate of change of the CO2 / N2 permeation rate ratio before and after high-temperature use is shown in the "Rate of Change of CO2 / N2 Permeation Rate Ratio" column of Table 1.

[0121] In the separation membrane composites of Examples 1-10, the area fraction of particulate particles was 5% or more (actually 30% or more). Furthermore, the change rate of the CO2 / N2 permeation rate ratio before and after high-temperature use was 0.9 or more. In Examples 1-10, the CO2 / N2 permeation rate ratio (i.e., separation performance) was maintained at the same level after high-temperature use as before, indicating that the occurrence of cracks caused by heating was suppressed. On the other hand, in the separation membrane composites of Comparative Examples 1-3, the area fraction of particulate particles was less than 5%. Furthermore, the change rate of the CO2 / N2 permeation rate ratio before and after high-temperature use was 0.7 or less. In Comparative Examples 1-3, the CO2 / N2 permeation rate ratio decreased significantly after high-temperature use, suggesting that cracks were caused by heating. It should be noted that in this embodiment, a separation membrane composite with a particulate area ratio exceeding 90% was not fabricated. However, in such a separation membrane composite, large voids (bridging structures) are easily formed in the particle-containing layer (between the support and the dense layer), which presumably reduces durability against high induction pressures.

[0122] Next, refer to Figure 7 and Figure 8 The separation of mixed substances using separation membrane complex 1 is explained. Figure 7This is a diagram showing the separation device 2. Figure 8 This is a diagram illustrating the process of separating mixed substances based on separation device 2.

[0123] In the separation device 2, a mixture containing multiple fluids (i.e., gas or liquid) is supplied to the separation membrane composite 1, causing highly permeable substances in the mixture to permeate through the separation membrane composite 1, thereby separating them from the mixture. The separation in the separation device 2 can be performed, for example, to extract highly permeable substances from the mixture, or to concentrate substances with low permeability.

[0124] The mixture (i.e., the mixed fluid) can be a mixture of gases containing multiple gases, a mixture of liquids containing multiple liquids, or a gas-liquid two-phase fluid containing both gases and liquids.

[0125] The mixture contains one or more of the following: hydrogen (H2), helium (He), nitrogen (N2), oxygen (O2), water (H2O), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides, ammonia (NH3), sulfur oxides, hydrogen sulfide (H2S), sulfur fluoride, mercury (Hg), arsine (AsH3), hydrogen cyanide (HCN), carbonyl sulfide (COS), C1-C8 hydrocarbons, organic acids, alcohols, thiols, esters, ethers, ketones, and aldehydes.

[0126] Nitrogen oxides refer to compounds of nitrogen and oxygen. Examples of nitrogen oxides include nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (also known as dinitrogen monoxide) (N2O), dinitrogen trioxide (N2O3), dinitrogen tetroxide (N2O4), and dinitrogen pentoxide (N2O5), all collectively referred to as NO. X (NOx) gas.

[0127] Sulfur oxides are compounds of sulfur and oxygen. Examples of sulfur oxides include sulfur dioxide (SO2) and sulfur trioxide (SO3), collectively referred to as SO42-SO ... X (Sox) gas.

[0128] Sulfur fluoride refers to compounds of fluorine and sulfur. Examples of sulfur fluoride mentioned above include disulfur difluoride (F-S-S-F, S=SF2), sulfur difluoride (SF2), sulfur tetrafluoride (SF4), sulfur hexafluoride (SF6), or disulfur decafluoride (S2F). 10 )wait.

[0129] Hydrocarbons with C1 to C8 carbon atoms are defined as hydrocarbons with one or more but fewer than eight carbon atoms. Hydrocarbons with C3 to C8 carbon atoms can be any of the following: straight-chain compounds, side-chain compounds, and cyclic compounds. Additionally, hydrocarbons with C2 to C8 carbon atoms can be any of the following: saturated hydrocarbons (i.e., hydrocarbons without double or triple bonds in the molecule) and unsaturated hydrocarbons (i.e., hydrocarbons with double and / or triple bonds in the molecule). Examples of hydrocarbons with C1 to C4 carbon atoms include methane (CH4), ethane (C2H6), ethylene (C2H4), propane (C3H8), propylene (C3H6), n-butane (CH3(CH2)2CH3), isobutane (CH(CH3)3), 1-butene (CH2=CHCH2CH3), 2-butene (CH3CH=CHCH3), or isobutene (CH2=C(CH3)2).

[0130] The organic acids mentioned above are carboxylic acids or sulfonic acids, etc. Examples of carboxylic acids include formic acid (CH2O2), acetic acid (C2H4O2), oxalic acid (C2H2O4), acrylic acid (C3H4O2), or benzoic acid (C6H5COOH), etc. Examples of sulfonic acids include ethanesulfonic acid (C2H6O3S), etc. These organic acids can be chain compounds or cyclic compounds.

[0131] The alcohols mentioned above include, for example, methanol (CH3OH), ethanol (C2H5OH), isopropanol (2-propanol) (CH3CH(OH)CH3), ethylene glycol (CH2(OH)CH2(OH)) or butanol (C4H9OH), etc.

[0132] Thiols are organic compounds with hydrogenated sulfur (SH) at their terminals, also known as Thiol or Thioalcohol. Examples of thiols include methanethiol (CH3SH), ethanethiol (C2H5SH), and 1-propanethiol (C3H7SH).

[0133] The esters mentioned above are, for example, formate esters or acetate esters.

[0134] The ethers mentioned above are, for example, dimethyl ether ((CH3)2O), methyl ethyl ether (C2H5OCH3), or diethyl ether ((C2H5)2O), etc.

[0135] The ketones mentioned above include acetone ((CH3)2CO), methyl ethyl ketone (C2H5COCH3), or diethyl ketone ((C2H5)2CO), etc.

[0136] The aldehydes mentioned above include acetaldehyde (CH3CHO), propionaldehyde (C2H5CHO), or butylaldehyde (C3H7CHO).

[0137] In the following description, we will take as an example a mixture of multiple gases that is separated by the separation device 2.

[0138] The separation device 2 includes: a separation membrane composite 1, a sealing part 21, a housing 22, two sealing components 23, a supply part 26, a first recovery part 27, and a second recovery part 28. The separation membrane composite 1, the sealing part 21, and the sealing components 23 are housed within the housing 22. The supply part 26, the first recovery part 27, and the second recovery part 28 are disposed outside the housing 22 and connected to the housing 22.

[0139] The sealing part 21 is: installed in the longitudinal direction of the support 11 (i.e., Figure 7 The sealing part 21 is a component that seals the two ends of the support body 11 in the left-right direction and covers the two end faces of the support body 11 in the longitudinal direction and the outer peripheral surface near the two end faces. The sealing part 21 prevents gas from flowing in and out relative to the two end faces of the support body 11. The sealing part 21 is, for example, a plate-shaped component made of glass or resin. The material and shape of the sealing part 21 can be appropriately changed. It should be noted that the sealing part 21 is provided with multiple openings that coincide with the multiple through holes 111 of the support body 11. Therefore, the two ends of each through hole 111 in the longitudinal direction of the support body 11 are not covered by the sealing part 21. Therefore, gas and the like can flow in and out from the two ends through the through holes 111.

[0140] The shape of the outer casing 22 is not limited, and it may be a generally cylindrical cylindrical component. The outer casing 22 is formed of, for example, stainless steel or carbon steel. The length direction of the outer casing 22 is generally parallel to the length direction of the separation membrane composite 1. At one end of the outer casing 22 in the length direction (i.e., Figure 7 A supply port 221 is provided at the left end of the housing 22, and a first discharge port 222 is provided at the other end. A second discharge port 223 is provided on the side of the housing 22. A supply section 26 is connected to the supply port 221. A first recovery section 27 is connected to the first discharge port 222. A second recovery section 28 is connected to the second discharge port 223. The internal space of the housing 22 is a sealed space isolated from the space surrounding the housing 22.

[0141] Two sealing components 23 are arranged circumferentially between the outer peripheral surface of the separation membrane composite 1 and the inner peripheral surface of the housing 22 near both ends along the length of the separation membrane composite 1. Each sealing component 23 is a generally annular component formed of a gas-impermeable material. The sealing component 23 is, for example, an O-ring formed of a flexible resin. The sealing components 23 are tightly fitted circumferentially to the outer peripheral surface of the separation membrane composite 1 and the inner peripheral surface of the housing 22. Figure 7 In the example shown, the sealing member 23 is sealed to the outer peripheral surface of the sealing part 21 and indirectly sealed to the outer peripheral surface of the separation membrane composite 1 by sandwiching the sealing part 21. The sealing member 23 is sealed between the outer peripheral surface of the separation membrane composite 1 and the inner peripheral surface of the housing 22, so that gas can hardly or completely pass through.

[0142] The supply unit 26 supplies the mixed gas to the interior space of the housing 22 via the supply port 221. The supply unit 26 is, for example, a blower or pump that pressurizes the mixed gas toward the housing 22. The blower or pump has a pressure regulating unit that regulates the pressure of the mixed gas supplied to the housing 22. The first recovery unit 27 and the second recovery unit 28 are, for example, storage containers for storing the gas discharged from the housing 22 or blowers or pumps for transferring the gas.

[0143] During the separation of the mixed gas, the separation membrane composite 1 is prepared by preparing the separation device 2 described above (step S21). Next, the supply unit 26 supplies a mixed gas containing multiple gases with different permeabilities to the separation membrane 12 into the internal space of the housing 22. For example, the main components of the mixed gas are CO2 and N2. The mixed gas may contain gases other than CO2 and N2. The pressure (i.e., the introduction pressure) of the mixed gas supplied from the supply unit 26 to the internal space of the housing 22 is, for example, 0.1 MPa to 20.0 MPa. The temperature for performing the mixed gas separation is, for example, 10°C to 150°C.

[0144] The mixed gas supplied from the supply unit 26 to the housing 22 is introduced into each through hole 111 of the support 11 from the left end of the separation membrane composite 1 in the figure, as shown by arrow 251. Highly permeable gases (e.g., CO2, hereinafter referred to as "highly permeable substances") in the mixed gas permeate through the separation membrane 12 and the support 11 disposed on the inner peripheral surface of each through hole 111 and are discharged from the outer peripheral surface of the support 11. Thus, the highly permeable substances are separated from the less permeable gases (e.g., N2, hereinafter referred to as "lowly permeable substances") in the mixed gas (step S22). The gas discharged from the outer peripheral surface of the support 11 (hereinafter referred to as "permeable substance") is recovered via the second outlet 223 using the second recovery unit 28, as shown by arrow 253. The pressure (i.e., permeation pressure) of the gas recovered via the second outlet 223 using the second recovery unit 28 is, for example, 0 MPa to 0.10 MPa (approximately 1 atmosphere).

[0145] In addition, gases in the mixed gas other than those that have permeated through the separation membrane 12 and the support 11 (hereinafter referred to as "impermeable substances") pass through the through holes 111 of the support 11 from left to right in the figure, as shown by arrow 252, and are recovered via the first discharge port 222 using the first recovery unit 27. The pressure of the gas recovered via the first discharge port 222 using the first recovery unit 27 is, for example, approximately the same as the inlet pressure. The impermeable substances may include, in addition to the low-permeability substances described above, high-permeability substances that do not permeate through the separation membrane 12.

[0146] Various modifications can be made to the above-mentioned separation membrane composite 1 and the manufacturing method of separation membrane composite 1.

[0147] In the above embodiments, in Figure 4 In step S14, the support 11 is immersed in the raw material solution. However, "immersion" here does not necessarily mean that the entire support 11 is in the raw material solution, but includes a state in which only the portion of the support 11 on the surface to which the separation membrane 12 is to be formed is in contact with the raw material solution. That is, the process of forming the separation membrane 12 is a process of heating the raw material solution to bring it into contact with the portion of the support 11 on the surface to which the separation membrane 12 is to be formed.

[0148] In the manufacture of the separation membrane composite 1 described above, the type of MOF in the seed crystals and the type of MOF in the MOF membrane formed using the feed solution may be different. That is, in the separation membrane 12, the type of MOF in the particulate particles 161 may be different from the type of MOF in other parts. Furthermore, the separation membrane 12 may contain two or more ligands. The separation membrane composite 1 can be manufactured using methods other than those described above.

[0149] In the separation device 2, substances other than those exemplified in the above description can be separated from the mixture.

[0150] The components in the above-described embodiments and their variations can be appropriately combined as long as they do not contradict each other.

[0151] Although the invention has been described in detail, the above description is exemplary and not limiting. Therefore, it can be said that numerous modifications and solutions can be adopted without departing from the scope of the invention.

[0152] Industrial availability

[0153] The separation membrane composite of the present invention can be used for the separation of various substances in various fields.

[0154] Explanation of reference numerals in the attached figures

[0155] 1 Separation Membrane Complex

[0156] 11 Support

[0157] 12 Separation Membrane

[0158] 16. Particle-containing layer

[0159] 17. Dense layer

[0160] 81 Seed Crystals

[0161] 161, 161a granular particles

[0162] Steps S11~S14, S21, S22

Claims

1. A separation membrane composite comprising: Porous supports; and The separation membrane, disposed on the support, is composed of a metal-organic structure. The separation membrane comprises: A particle-containing layer, which is in contact with the support, wherein the granular particles of the metal-organic structure are dispersed in the particle-containing layer; and A dense layer, which is a layer in contact with the particle-containing layer on the side opposite to the support, and which does not contain the granular particles. In a cross-section perpendicular to the surface of the separation membrane, the particulate particles occupy an area fraction of 5 to 90% in the particle-containing layer.

2. The separation membrane composite according to claim 1, wherein, The granular particles include aggregates of microparticles.

3. The separation membrane composite according to claim 1, wherein, The average particle size of the granular particles is 10–500 nm.

4. The separation membrane composite according to claim 1, wherein, The thickness of the particle-containing layer is less than 1 μm.

5. The separation membrane composite according to any one of claims 1 to 4, wherein, The average thickness of the separation membrane is 1.1 to 20 times the thickness of the particle-containing layer.

6. A method for manufacturing a separation membrane composite, comprising the following steps: a) Prepare microparticles of metal-organic structures; b) Prepare a dispersion containing an organic solvent and water as solvents, and containing the microparticles and a pH adjuster, wherein the aggregates of the microparticles are dispersed as seed crystals; c) Using the dispersion, the seed crystals are attached to a porous support; and d) The support is immersed in the raw material solution, and a separation membrane composed of a metal-organic structure is formed on the support by solvothermal synthesis.

7. The method for manufacturing the separation membrane composite according to claim 6, wherein, The dispersion contains an organic solvent of 90% by volume or more and a water content of 10% by volume or less.

8. The method for manufacturing the separation membrane composite according to claim 6 or 7, wherein, The average particle size of the aggregates in the dispersion is 10–500 nm.

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